The objective of the present invention is to improve on the wooden truss fabricating apparatus in the above referenced application in two main areas. Firstly, the construction and mode of operation of the dual articulated and counterbalanced boom arrangement has been greatly improved by rendering it more simplified and positive in its operation and also safer to use for its intended purpose. Secondly, a unique fabricating jig for the trailer bed or chassis of the apparatus has been provided as a principal component of the present invention. This highly versatile jig enables the rapid construction at the job site of wooden trusses with high precision and dimensional stability and uniformity, resulting from the strategic placement on the jig of a series of swivel stops and permanent stops to position truss lumber on the jig prior to the application of nailing plates thereto by means of a power press carried by the articulated boom structure. Means are also provided on the jig to precisely locate the peak of a truss undergoing fabrication and to locate a splice with repetitive accuracy in the lower main chord of each truss.
By means of the highly versatile precision jig arrangement, the jig can be completely adjusted or "set up" on the job site before the placement of the truss lumber thereon, thus eliminating the necessity for the operator to delay setting up the jig until the truss lumber is cut. This constitutes a very important aspect of the invention.